A patient who has fully compensated respiratory acidosis becomes severely hypoxic. If her lungs are not too severely compromised, what might her gases now appear to be?

Question

a. Fully compensated metabolic acidosis
b. Fully compensated metabolic alkalosis
c. Fully compensated respiratory alkalosis
d. No change

Answer 1

ANS: B
Consider a patient with a compensated respiratory acidosis who has an arterial pH of 7.38, a PaCO2 of 58 mm Hg, and an HCO3– of 33 mEq/L. If this patient becomes severely hypoxic, the hypoxia may stimulate increased alveolar ventilation if lung mechanics are not too severely de-ranged. This would acutely lower the PaCO2, possibly raising the pH to the alkalotic side of normal. For example, the patient's blood gas values might now be as follows: pH of 7.44, PaCO2 of 50 mm Hg, and HCO3– of 33 mEq/L.